CoFe/Ni multilayer film with perpendicular anisotropy for microwave assisted magnetic recording

Abstract

A spin transfer oscillator with a seed/SIL/spacer/FGL/capping configuration is disclosed with a composite seed layer made of Ta and a metal layer having a fcc(111) or hcp(001) texture to enhance perpendicular magnetic anisotropy (PMA) in an overlying (A1/A2) X laminated spin injection layer (SIL). Field generation layer (FGL) is made of a high Bs material such FeCo. Alternatively, the STO has a seed/FGL/spacer/SIL/capping configuration. The SIL may include a FeCo layer that is exchanged coupled with the (A1/A2) X laminate (x is 5 to 50) to improve robustness. The FGL may include an (A1/A2) Y laminate (y=5 to 30) exchange coupled with the high Bs layer to enable easier oscillations. A1 may be one of Co, CoFe, or CoFeR where R is a metal, and A2 is one of Ni, NiCo, or NiFe. The STO may be formed between a main pole and trailing shield in a write head.

We claim: 
     
       1. A spin transfer oscillator (STO) structure in a spintronic device, comprising:
 (a) a composite seed layer comprising at least a lower Ta layer formed on a substrate and a metal (M1) layer having a fcc(111) or hcp(001) crystal structure contacting the lower Ta layer; 
 (b) a laminated spin injection layer (SIL) with high perpendicular magnetic anisotropy (PMA) and with a (A1/A2) X  configuration contacting a top surface of the seed layer wherein x is in a range from 5 to 50, and a thickness (t2) of each A2 magnetic layer is greater than a thickness (t1) of each A1 magnetic layer, and at least one of the A1 and A2 magnetic layers is an alloy of Co or an alloy of Ni; 
 (c) a non-magnetic spacer formed on the SIL; 
 (d) a composite field generation layer (FGL) having a (A1/A2) Y /FeCo or (A1/A2) Y /FeCoM configuration where M is one or more of Al, Ge, Si, Ga, B, C, Se, and Sn that is formed on the non-magnetic spacer, and wherein the (A1/A2) Y  in the composite FGL is a laminate having PMA and that contacts a top surface of the non-magnetic spacer, and is one of (co/NiFe) Y , (Co/NiCo) Y , (CoFe/NiFe) Y , (CoFe/NiCo) Y , (CoFeR/Ni) Y , (CoFeR/NiFe) Y , or (CoFeR/NiCo) Y  where y is from 5 to 30, R is one of Ru, Rh, Pd, Ti, Zr, Hf, Ni, Cr, Mg, Mn, or Cu; and 
 (e) a capping layer contacting a top surface of the FGL. 
 
     
     
       2. The STO structure of  claim 1  wherein the FeCo is a high Bs layer that is exchange coupled with one of the (A1/A2) Y  laminates to generate a partial PMA in the high Bs layer. 
     
     
       3. The STO structure of  claim 2  wherein the SIL is further comprised of a FeCo layer to give a composite SIL having an (A1/A2) X /FeCo configuration in which the FeCo layer in the composite SIL is exchange coupled with the (A1/A2) X  laminate in the SIL to generate a more robust SIL, said FeCo layer in the SIL contacts a bottom surface of the non-magnetic spacer. 
     
     
       4. The STO structure of  claim 1  wherein the non-magnetic spacer is comprised of Cu to give a CPP-GMR configuration or is made of AlOx, MgO, TiOx, TiAlOx, MgZnOx, or ZnOx to give a CPP-TMR configuration.